Extensions

Before beginning the experiment, have students create a class chart of their predicted investigation results. After the experiment, lead a class discussion comparing students’ predictions to the results and possible reasons for the differences.

Encourage students to ask additional questions and think of variations to the experiment.

The levels of some heat-trapping (or “greenhouse”) gases in the atmosphere (especially carbon dioxide, methane and ozone) have increased during the last several decades. Many scientists believe these will cause additional warming of Earth’s surface. Ask students, Based on what you have observed, do you think that this is a reasonable prediction? Encourage students to find more information about this topic in the library or the Internet.

If using the student book, Mr. Slaptail's Curious Contraption, ask students, Based on what you have learned in this activity, how do you think Mr. Slaptail might have improved upon the design of his water heater?